There exists a plurality of different types of alternating current (AC) machines including induction machines (IM) and synchronous machines. The synchronous machines further comprise synchronous reluctance machines (SynRM) and permanent magnet machines (PM). For each AC motor type there is an appropriate control scheme according to which a motor controller drives the AC motor. The operator must know what kind of AC motor is connected so that he can select an appropriate control scheme. However, it can be difficult for the operator to identify the type of the motor because the appearance of the different types of AC motors can be very similar.
US 2008/0074070 discloses a method for autonomously identifying a type of a motor based on a characteristic value of the motor. A characteristic value of the motor is measured and compared to a known characteristic value. The type of the motor is identified based on the comparison. For example, two traction motors with different windings may be identified on the basis of their turning direction when the motors are excited with a phase sequence that causes the motors to turn in opposite directions.
JP11055991 discloses a SynRM with means for detecting a rotor position, and a method for driving the SynRM with help of the position information.
U.S. Pat. No. 6,570,358 B2 discloses an AC motor control apparatus having a machine type identification means with which the type of the connected machine is identified. The machine type is identified by measuring the inductance of the direct axis (d-axis) and the inductance of the quadrature axis (q-axis) which is orthogonal to the d-axis and has advanced by 90° in electrical angle. The identification is based on the relationship in magnitude between the measured inductances of the d-axis and q-axis. The control of AC motors according to motor control schemes is also disclosed.
However, the above-mentioned method for machine type identification is complicated to implement. Thus, there is a need for methods which can identify the AC machine type in a simple and uncomplicated manner.